Integrating ERC-20 Tokens with Web3.js

Below is a simple but realistic integration workflow you can adapt to any dApp.

1. Install Web3.js

npm install web3

2. Connect to a Wallet (e.g., MetaMask)

const web3 = new Web3(window.ethereum);

await window.ethereum.request({ method: "eth_requestAccounts" });

3. Load the Token Contract

You'll need the contract ABI and its deployed address - normally available from your developer or the smart contract repository.

const token = new web3.eth.Contract(abi, tokenAddress);

4. Read the User's Token Balance

const accounts = await web3.eth.getAccounts();

const balance = await token.methods.balanceOf(accounts[0]).call();

5. Send a Transfer

await token.methods.transfer(receiver, amount).send({ from: accounts[0] });

This is the foundation of most ERC-20 interactions, regardless of whether your token came from ethereum token development services or a custom project.

Integrating Tokens with Ethers.js

Many developers prefer Ethers.js due to its simplicity and reliability.

1. Install Ethers.js

npm install ethers

2. Connect to Provider + Signer

const provider = new ethers.providers.Web3Provider(window.ethereum);

await provider.send("eth_requestAccounts", []);

const signer = provider.getSigner();

3. Load Your Token Contract

const token = new ethers.Contract(tokenAddress, abi, signer);

4. Fetch Token Balance

const balance = await token.balanceOf(await signer.getAddress());

5. Execute a Transfer

await token.transfer(receiver, amount);

Ethers.js also simplifies working with units and handling gas estimation - helpful when working with any ethereum token development solutions or custom smart contracts.

Practical Tips for Smooth Token Integration

Here are insights commonly shared in technical documentation, audits, and code reviews:

✔ Ensure the token fully follows the ERC-20 standard

Missing or modified functions often cause unexpected integration issues.

✔ Validate inputs on the frontend

Even trivial checks (empty fields, malformed addresses) prevent broken transactions.

✔ Check network compatibility

Guide users when they are on the wrong chain.

✔ Use events to update UI

Listening to Transfer events keeps balance displays accurate.

✔ Test with local blockchain environments

Tools like Hardhat or Foundry help you catch issues early.

These practical habits apply to any ERC-20, erc 20 token, eth erc20 workflow, regardless of whether you're building alone or with a token development company.

Common Integration Mistakes to Avoid

• Using an incorrect or outdated ABI  

• Forgetting to convert values using parseUnits  

• Not handling asynchronous wallet switching  

• Assuming the user is already connected  

• Hardcoding RPC URLs without fallbacks